Blower apparatus

ABSTRACT

This blower apparatus includes an air blowing portion including a plurality of flat plates arranged with an axial gap defined between adjacent ones of the flat plates; a motor portion arranged to rotate the air blowing portion; and a housing arranged to house the air blowing portion and the motor portion. The flat plates include an air hole arranged to pass therethrough in an axial direction. Once the air blowing portion starts rotating, an air flow traveling radially outward is generated between the flat, plates by viscous drag of surfaces of the flat plates and a centrifugal force. Thus, gas supplied through the air inlet and the air hole travels radially outwardly of the air blowing portion. Accordingly, a reduced thickness of the blower apparatus does not result in a significant reduction in the air blowing efficiency.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a blower apparatus.

2. Description of the Related Art

A centrifugal blower apparatus which generates an air flow traveling radially outward by rotating an impeller including a plurality of blades is known. A known blower apparatus including an impeller is described in, for example, JP-A 2008-88985.

In the blower apparatus described in JP-A 2008-88985, a plurality of blades referred to as fan blades push surrounding gas to generate air flows traveling radially outward.

SUMMARY OF THE INVENTION

In recent years, there has still been a demand for reductions in the size and thickness of electronic devices. Accordingly, there has also been a demand for a reduction in the thickness of blower apparatuses used to cool the interiors of the electronic devices.

Here, in the case where an impeller is used to generate air flows, as in the blower apparatus described in JP-A 2008-88985, air flows pushed by a blade leak from axially upper and lower ends of the blade while the impeller is rotating. As a result, air pressure is lower at the axially upper and lower ends of the blade than in the vicinity of an axial middle of the blade. Accordingly, a reduction in the thickness of the blower apparatus, which involves a reduction in the axial dimension of the impeller, will result in a failure to secure sufficient air blowing efficiency.

An object of the present invention is to provide a technique for realizing a centrifugal blower apparatus which is excellent in air blowing efficiency.

A blower apparatus according to a preferred embodiment of the present invention includes an air blowing portion arranged to rotate about a central axis extending in a vertical direction; a motor portion arranged to rotate the air blowing portion; and a housing arranged to house the air blowing portion and the motor portion. The housing includes a lower plate portion arranged to cover at least a portion of a lower side of the air blowing portion, and support the motor portion; an upper plate portion arranged above the lower plate portion, and including an air inlet arranged to pass therethrough in an axial direction; and a side wall portion arranged to cover a lateral side of the air blowing portion between the upper plate portion and the lower plate portion, and including an air outlet arranged to face in a radial direction at at least one circumferential position. The air blowing portion includes a plurality of flat plates arranged in the axial direction with an axial gap defined between adjacent ones of the flat plates. At least one of the flat plates includes an air hole arranged to pass therethrough in the axial direction. Each air hole is arranged to be in communication with a space radially outside of the air blowing portion through the axial gap.

According to the above preferred embodiment of the present invention, once the air blowing portion starts rotating, an air flow traveling radially outward is generated in the axial gap between the adjacent ones of the flat plates by viscous drag of surfaces of the flat plates and a centrifugal force. Thus, gas supplied through the air inlet and the air hole travels radially outwardly of the air blowing portion. Since the air flow is generated between the flat plates, the air flow does not easily leak upwardly or downwardly, and thus, an improvement in air blowing efficiency is achieved. Accordingly, a reduced thickness of the blower apparatus according to the above preferred embodiment of the present invention does not result in a significant reduction in the air blowing efficiency. In addition, the blower apparatus according to the above preferred embodiment of the present invention is superior to a comparable centrifugal fan including an impeller in terms of being silent.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a blower apparatus according to a first preferred embodiment of the present invention.

FIG. 2 is a top view of the blower apparatus according to the first preferred embodiment.

FIG. 3 is a sectional view of the blower apparatus according to the first, preferred embodiment.

FIG. 4 is an exploded perspective view of the blower apparatus according to the first preferred embodiment.

FIG. 5 is a partial sectional view of the blower apparatus according to the first preferred embodiment.

FIG. 6 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 7 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 8 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 9 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 10 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 11 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 12 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 13 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 14 is a partial sectional view of a blower apparatus according to a modification of the first preferred embodiment.

FIG. 15 is a top view of a blower apparatus according to a modification of the first preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, blower apparatuses according to preferred embodiments of the present, invention will be described. It is assumed herein that a side on which an upper plate portion is arranged with respect to a lower plate portion is an upper side, and the shape of each member or portion and relative positions of different members or portions will be described based on the above assumption. It should be noted, however, that the above definition of the upper and lower sides is not meant, to restrict in any way the orientation of a blower apparatus according to any preferred embodiment of the present invention at the time of manufacture or when in use.

1. First Preferred Embodiment

FIG. 1 is a perspective view of a blower apparatus 1 according to a first preferred embodiment of the present invention. FIG. 2 is a top view of the blower apparatus 1. FIG. 3 is a sectional view of the blower apparatus 1 taken along line A-A in FIG. 2. FIG. 4 is an exploded perspective view of the blower apparatus 1. FIG. 5 is a partial sectional view of the blower apparatus 1. The blower apparatus 1 is a centrifugal blower apparatus designed to generate an air flow traveling radially outward by rotating an air blowing portion 40. The blower apparatus 1 is, for example, installed in an electronic device, such as, for example, a personal computer, to cool an interior thereof. Note that the blower apparatus 1 according to a preferred embodiment of the present invention may alternatively be used for other purposes.

Referring to FIGS. 1 to 4, the blower apparatus 1 includes a housing 20, a motor portion 30, and the air blowing portion 40.

The housing 20 is a case arranged to house the motor portion 30 and the air blowing portion 40. The housing 20 includes a lower plate portion 21, a side wall portion 22, and an upper plate portion 23.

The lower plate portion 21 is arranged to define a bottom portion of the housing 20. The lower plate portion 21 is arranged to extend radially below the air blowing portion 40 to cover at least a portion of a lower side of the air blowing portion 40. In addition, the lower plate portion 21 is arranged to support the motor portion 30.

The side wall portion 22 is arranged to extend upward from the lower plate portion 21. The side wall portion 22 is arranged to cover a lateral side of the air blowing portion 40 between the lower plate portion 21 and the upper plate portion 23. In addition, the side wall portion 22 includes an air outlet 201 arranged to face in a radial direction at one circumferential position. In the present preferred embodiment, the lower plate portion 21 and the side wall portion 22 are defined integrally with each other. Note that, the lower plate portion 21 and the side wall portion 22 may alternatively be defined by separate members.

The upper plate portion 23 is arranged to define a cover portion of the housing 20. The upper plate portion 23 is arranged to extend radially above the lower plate portion 21. In addition, the upper plate portion 23 includes an air inlet 202 arranged to pass therethrough in an axial direction. In other words, the upper plate portion 23 includes an inner edge portion 231 arranged to define the air inlet 202. The air inlet 202 is, for example, circular and is centered on a central axis 9 in a plan view.

The motor portion 30 is a driving portion arranged to rotate the air blowing portion 40. Referring to FIG. 5, the motor portion 30 includes a stationary portion 31 and a rotating portion 32. The stationary portion 31 is fixed to the lower plate portion 21, The stationary portion 31 is thus arranged to be stationary relative to the housing 20. The rotating portion 32 is supported to be rotatable about the central axis 9 with respect to the stationary portion 31.

The stationary portion 31 includes a stator fixing portion 311, a stator 312, and a bearing housing 313.

The stator fixing portion 311 is fitted in a fixing hole 211 defined in the lower plate portion 21. As a result, the stator fixing portion 311 is fixed to the lower plate portion 21. The stator fixing portion 311 is arranged to extend upward from the fixing hole 211 to assume a cylindrical shape with the central axis 9 as a center thereof. The stator 312 is fixed to an outer circumferential portion of an upper portion of the stator fixing portion 311.

The stator 312 is an armature arranged to generate magnetic flux in accordance with electric drive currents supplied from an external source. The stator 312 is arranged to annularly surround the central axis 9, which extends in a vertical direction. The stator 312 includes, for example, an annular stator core defined by laminated steel sheets, and conducting wires wound around the stator core.

The bearing housing 313 is a member being cylindrical and having a closed bottom. Specifically, the bearing housing 313 includes a disk-shaped bottom portion, and a cylindrical portion arranged to extend upward from the bottom portion. The bearing housing 313 is fixed to an inner circumferential surface of the stator fixing portion 311.

The rotating portion 32 includes a shaft 321, a hub 322, a bearing member 323, and a magnet 324.

The shaft 321 is a member arranged to extend along the central axis 9. The shaft 321 according to the present preferred embodiment includes a columnar portion arranged inside of a first cylindrical portion 512, which will be described below, and arranged to extend with the central axis 9 as a center thereof, and a disk-shaped portion arranged to extend radially from a lower end portion of the columnar portion.

The hub 322 is fixed to the shaft 321. The hub 322 is made up of a hub body member 51 and a flange member 52.

The hub body member 51 includes a first top plate portion 511, the first cylindrical portion 512, a second cylindrical portion 513, and a magnet holding portion 514.

The first top plate portion 511 is a disk-shaped portion arranged to extend radially with the central axis 9 as a center thereof. The first top plate portion 511 is arranged above the stator 312. The first top plate portion 511 has a recessed portion 515 recessed from an upper surface thereof at an outer edge portion thereof.

The first cylindrical portion 512 is arranged to extend downward from the first top plate portion 511 to assume a cylindrical shape with the central axis 9 as a center thereof. The columnar portion of the shaft 321 is housed in the first cylindrical portion 512. In addition, the shaft 321 is fixed to the first cylindrical portion 512.

The second cylindrical portion 513 is arranged to extend downward from the first top plate portion 511 to assume a cylindrical shape with the central axis 9 as a center thereof. The second cylindrical portion 513 is arranged to have an inside diameter greater than an outside diameter of the first cylindrical portion 512. In other words, the second cylindrical portion 513 is arranged radially outside of the first cylindrical portion 512.

The magnet holding portion 514 is arranged to extend downward from a radially outer end of the first top plate portion 511 to assume a cylindrical shape with the central axis 9 as a center thereof. The magnet holding portion 514 is arranged radially outside of the stator 312. The magnet 324 is fixed to an inner circumferential surface of the magnet holding portion 514.

The flange member 52 includes an outer wall portion 521, a second top plate portion 522, and a flat plate holding portion 523.

The outer wall portion 521 is a cylindrical portion arranged to extend in the vertical direction with the central axis 9 as a center thereof. The outer wall portion 521 is arranged to extend along an outer circumferential surface of the magnet holding portion 514 of the hub body member 51.

The second top plate portion 522 is arranged to extend radially inward from an upper end portion of the outer wall portion 521 to assume the shape of a circular ring. The second top plate portion 522 is arranged in the recessed portion 515, which is defined in the upper surface of the first top plate portion 511 of the hub body member 51. In addition, the upper surface of the first top plate portion 511 and an upper surface of the second top plate portion 522 are arranged at the same axial position.

The flat plate holding portion 523 is arranged to extend radially outward from a lower end portion of the outer wall portion 521. The flat plate holding portion 523 is arranged to hold the air blowing portion 40 on a radially outer side of the magnet holding portion 514 of the hub body member 51. In the present preferred embodiment, the air blowing portion 40 is mounted on an upper surface of the flat plate holding portion 523. The flat, plate holding portion 523 is thus arranged to hold a plurality of flat plates 410 included in the air blowing portion 40.

The bearing member 323 is a cylindrical member arranged to extend in the vertical direction with the central axis 9 as a center thereof. The bearing member 323 is arranged to extend along an outer circumferential surface of the first cylindrical portion 512 of the hub body member 51. In addition, the bearing member 323 is fixed to the outer circumferential surface of the first cylindrical portion 512. The cylindrical portion of the bearing housing 313 is arranged radially outside of the bearing member 323 and radially inside of the second cylindrical portion 513 of the hub body member 51.

The magnet 324 is fixed to the inner circumferential surface of the magnet holding portion 514 of the hub body member 51. In addition, the magnet 324 is arranged radially outside of the stator 312. The magnet 324 according to the present preferred embodiment is in the shape of a circular ring. A radially inner surface of the magnet 324 is arranged radially opposite to the stator 312 with a slight gap therebetween. In addition, an inner circumferential surface of the magnet 324 includes north and south poles arranged to alternate with each other in a circumferential direction. Note that a plurality of magnets may be used in place of the magnet 324 in the shape of a circular ring. In the case where the plurality of magnets are used, the magnets are arranged in the circumferential direction such that north and south poles of the magnets alternate with each other.

As illustrated in an enlarged view in FIG. 5, a lubricating fluid 300 is arranged between the bearing housing 313 and a combination of the shaft 321, the bearing member 323, and the hub body member 51. A polyolester oil or a diester oil, for example, is used as the lubricating fluid 300. The shaft 321, the hub 322, and the bearing member 323 are supported to be rotatable with respect, to the bearing housing 313 through the lubricating fluid 300. Thus, in the present preferred embodiment, the bearing housing 313, which is a component of the stationary portion 31, the combination of the shaft 321, the bearing member 323, and the hub body member 51, each of which is a component of the rotating portion 32, and the lubricating fluid 300 together define a fluid dynamic bearing.

A surface of the lubricating fluid 300 is defined in a seal portion 301, which is a gap between an outer circumferential surface of the bearing housing 313 and an inner circumferential surface of the second cylindrical portion 513 of the hub body member 51. In the seal portion 301, the distance between the outer circumferential surface of the bearing housing 313 and the inner circumferential surface of the second cylindrical portion 513 is arranged to increase with decreasing height. In other words, in the seal portion 301, the distance between the outer circumferential surface of the bearing housing 313 and the inner circumferential surface of the second cylindrical portion 513 is arranged to increase with increasing distance from the surface of the lubricating fluid 300. Since the radial width of the seal portion 301 thus increases with decreasing height, the lubricating fluid 300 is attracted upward in the vicinity of the surface of the lubricating fluid 300. This reduces the likelihood that the lubricating fluid 300 will leak out of the seal portion 301.

Use of the fluid dynamic bearing as a bearing mechanism that connects the stationary portion 31 and the rotating portion 32 allows the rotating portion 32 to rotate stably. Thus, the likelihood of an occurrence of an unusual sound from the motor portion 30 can be reduced.

Once electric drive currents are supplied to the stator 312 in the motor portion 30 as described above, magnetic flux is generated around the stator 312. Then, interaction between the magnetic flux of the stator 312 and magnetic flux of the magnet 324 produces a circumferential torque between the stationary portion 31 and the rotating portion 32, so that the rotating portion 32 is caused to rotate about the central axis 9 with respect to the stationary portion 31. The air blowing portion 40, which is held by the flat plate holding portion 523 of the rotating portion 32, is caused to rotate about the central axis 9 together with the rotating portion 32.

Referring to FIGS. 4 and 5, the air blowing portion 40 includes the plurality of flat plates 410 and a plurality of spacers 420. The flat plates 410 and the spacers 420 are arranged to alternate with each other in the axial direction. In addition, adjacent ones of the flat plates 410 and the spacers 420 are fixed to each other through, for example, adhesion.

Referring to FIGS, 4 and 5, in the present preferred embodiment, the flat plates 410 include a top flat plate 411, which is arranged at the highest position, a bottom flat plate 412, which is arranged at the lowest position, and four intermediate flat plates 413, which are arranged below the top flat plate 411 and above the bottom flat plate 412. That is, the number of flat plates 410 included in the air blowing portion 40 according to the present preferred embodiment is six. The flat plates 410 are arranged in the axial direction with an axial gap 400 defined between adjacent ones of the flat plates 410.

Each flat plate 410 is made of, for example, a metal material, such as stainless steel, or a resin material. Each flat plate 410 may alternatively be made of, for example, paper. In this case, paper including a glass fiber, a metal wire, or the like in addition to plant fibers may be used. The flat plate 410 is able to achieve higher dimensional accuracy when the flat plate 410 is made of a metal material than when the flat plate 410 is made of a resin material.

In the present preferred embodiment, each of the top flat plate 411 and the four intermediate flat plates 413 is arranged to have the same shape and size. Referring to FIGS. 1, 2, and 5, each of the top flat plate 411 and the intermediate flat plates 413 includes an inner annular portion 61, an outer annular portion 62, a plurality of ribs 63, and a plurality of air holes 60. In the present preferred embodiment, the number of ribs 63 and the number of air holes 60 included in each of the top flat plate 411 and the intermediate flat plates 413 are both five.

The inner annular portion 61 is an annular portion centered on the central axis 9. The inner annular portion 61 has a central hole 65 (see FIG. 4) arranged to pass therethrough in the vertical direction in a center thereof. The outer annular portion 62 is an annular portion arranged radially outside of the inner annular portion 61 with the central axis 9 as a center thereof. Each rib 63 is arranged to join the inner annular portion 61 and the outer annular portion 62 to each other. Each air hole 60 is arranged to be in communication with a space radially outside of the air blowing portion 40 through the axial gap(s) 400 adjacent to the flat plate 410 including the air hole 60 on the upper and/or lower sides of the flat plate 410. Each air hole 60 is arranged at a position overlapping with the air inlet 202 of the housing 20 when viewed in the axial direction.

The bottom flat plate 412 is an annular and plate-shaped member centered on the central axis 9. The bottom flat plate 412 has a central hole 65 arranged to pass therethrough in the vertical direction in a center thereof.

Referring to FIG. 4, each spacer 420 is a member in the shape of a circular ring. The spacers 420 are arranged between the flat plates 410 to secure the axial gaps 400 between the flat plates 410. Each spacer 420 has a central hole 429 arranged to pass therethrough in the vertical direction in a center thereof. The motor portion 30 is arranged in the central holes 65 of the flat plates 410 and the central holes 429 of the spacers 420.

Each spacer 420 is arranged at a position axially coinciding with the inner annular portion 61 of each of the top flat plate 411 and the intermediate flat plates 413. Thus, the spacer 420 is arranged in a region in the

corresponding axial gap 400, the region covering only a portion of the radial extent of the corresponding axial gap 400.

Once the motor portion 30 is driven, the air blowing portion 40 is caused to rotate together with the rotating portion 32. As a result, viscous drag of a surface of each flat plate 410 and a centrifugal force together generate an air flow traveling radially outward in the vicinity of the surface of the flat plate 410. Thus, an air flow traveling radially outward is generated in each of the axial gaps 400 between the flat plates 410. Thus, gas above the housing 20 is supplied to each axial gap 400 through the air inlet 202 of the housing 20 and the air holes 60 of the top flat plate 411 and the intermediate flat plates 413, and is discharged out of the blower apparatus 1 through the air outlet 201, which is defined in a side portion of the housing 20.

Here, each flat plate 410 is arranged to have an axial thickness of about 0.1 mm. Meanwhile, each axial gap 400 is arranged to have an axial dimension of about 0.3 mm. The axial dimension of the axial gap 400 is preferably in the range of 0.2 mm to 0.5 mm. An excessively large axial dimension of the axial gap 400 would lead to a separation between an air flow generated by a lower surface of the flat plate 410 on the upper side and an air flow generated by an upper surface of the flat plate 410 on the lower side during rotation of the air blowing portion 40. This separation could result in a failure to generate sufficient static pressure in the axial gap 400 to discharge a sufficient volume of air. Moreover, an excessively large axial dimension of the axial gap 400 would make it difficult to reduce the axial dimension of the blower apparatus 1. Accordingly, in this blower apparatus 1, the axial dimension of the axial gap 400 is arranged to be in the range of 0.2 mm to 0.5 mm. This arrangement allows the blower apparatus 1 to achieve a reduced thickness while allowing an increase in the static pressure in the axial gap 400 to discharge a sufficient volume of air.

Each of the top flat plate 411 and the intermediate flat plates 413 includes the air holes 60. Accordingly, in each of the top flat plate 411 and the intermediate flat plates 413, the outer annular portion 62, which is arranged radially outside of the air holes 60, defines an air blowing region which generates an air flow in the vicinity of a surface thereof. Meanwhile, the bottom flat plate 412 includes no air hole 60. Therefore, in an upper surface of the bottom flat plate 412, an entire region radially outside of a portion of the bottom flat plate 412 which makes contact with the spacer 420 defines an air blowing region. In other words, in the upper surface of the bottom flat plate 412, a region which axially coincides with the air holes 60 and the ribs 63 of the top flat plate 411 and the intermediate flat plates 413, and a region which axially coincides with the outer annular portions 62 thereof, together define the air blowing region. In addition, in a lower surface of the bottom flat plate 412, an entire region radially outside of a portion of the bottom flat plate 412 which makes contact with the flat plate holding portion 523 defines an air blowing region. Notice that an air flow is generated by a lower surface of the flat plate holding portion 523 as well.

As described above, the bottom flat plate 412 has air blowing regions wider than the air blowing regions of the top flat plate 411 and the intermediate flat plates 413. Therefore, the axial gap 400 between the lowest one of the intermediate flat plates 413 and the bottom flat plate 412 is able to have higher static pressure than any other axial gap 400.

Air flows passing downward through the air inlet 202 and the air holes 60 are drawn radially outward in each axial gap 400. Therefore, the air flows passing through the air holes 60 become weaker as they travel downward. In the present preferred embodiment, the bottom flat plate 412 is arranged to have an air blowing region wider than the air blowing regions of the top flat plate 411 and the intermediate flat plates 413 to cause a stronger air flow to be generated in the lowest one of the axial gaps 400 than in any other axial gap 400 to cause the air flows passing downward through the air holes 60 to be drawn toward the lowest axial gap 400. Thus, a sufficient volume of gas is supplied to the lowest axial gap 400 as well. As a result, the air blowing portion 40 achieves improved air blowing efficiency.

In a related-art blower apparatus that generates air flows by rotating an impeller including a plurality of blades, air flows generated by the impeller leak at upper and lower end portions of the impeller. This leakage of the air flows occurs regardless of the axial dimension of the blower apparatus. Therefore, as the blower apparatus is designed to be thinner, an effect of this leakage on the blower apparatus as a whole becomes greater, resulting in lower air blowing efficiency. Meanwhile, in the blower apparatus 1 according to the present preferred embodiment, the air flows are generated in the vicinity of the surfaces of the flat plates 410, and therefore, the air flows do not easily leak upward or downward. Therefore, even when the axial dimension of the air blowing portion 40, which generates the air flows, is reduced, a reduction in air blowing efficiency due to leakages of the air flows does not easily occur. That is, even when the blower apparatus 1 has a reduced thickness, a reduction in air blowing efficiency thereof does not easily occur.

In addition, in a blower apparatus including an impeller, periodic noise occurs owing to the shape, number, arrangement, and so on of blades. However, this blower apparatus 1 is superior to a comparable blower apparatus including an impeller in terms of being silent, because the air flows are generated by the viscous drag of the surface of each flat plate 410 and the centrifugal force in the blower apparatus 1.

In addition, from the viewpoint of P-Q characteristics (i.e., flow rate-static pressure characteristics), the blower apparatus 1 including the flat plates 410 is able to produce a higher static pressure in a low flow rate region than the blower apparatus including the impeller. Therefore, when compared to the blower apparatus including the impeller, the blower apparatus 1 is suitable for use in a densely packed case, from which only a relatively small volume of air can be discharged. Examples of such cases include cases of electronic devices, such as, for example, personal computers.

In the present preferred embodiment, the top flat plate 411 and all the intermediate flat plates 413 include the air holes 60. Accordingly, all the axial gaps 400 are in axial communication with a space above the housing 20 through the air inlet 202 and the air holes 60.

Referring to FIG. 2, the air inlet 202 is centered on the central axis 9. That is, a center of the air inlet 202 coincides with the central axis 9. Meanwhile, the air blowing portion 40 is also centered on the central axis 9. Accordingly, differences in pressure do not easily occur at different circumferential positions in the air blowing portion 40. This contributes to reducing noise. It is assumed that, the term “coincide” as used here includes not only “completely coincide” but also “substantially coincide”.

Referring to FIG. 5, the top flat plate 411 is arranged axially below and radially inward of the inner edge portion 231 of the upper plate portion 23 when viewed in the axial direction, the inner edge portion 231 defining the air inlet 202. In addition, an axial distance D1 between an outer edge of the top flat plate 411 and the inner edge portion 231 of the upper plate portion 23 is arranged to be smaller than a radial distance D2 between the outer edge of the top flat, plate 411 and the inner edge portion 231 of the upper plate portion 23.

A pressure generated by the rotation of the air blowing portion 40 spreads only a certain distance from a surface of the top flat plate 411. Therefore, a large axial distance between the top flat plate 411 and the inner edge portion 231, which defines the air inlet 202, would result in an easy occurrence of a backflow. In the present preferred embodiment, the axial distance D1 between the top flat plate 411 and the inner edge portion 231 is arranged to be smaller than the radial distance D2 to reduce the likelihood of an occurrence of a backflow phenomenon.

2. Example Modifications

While a preferred embodiment of the present invention has been described above, it is to be understood that the present invention is not limited to the above-described preferred embodiment.

FIG. 6 is a partial sectional view of a blower apparatus 1A according to a modification of the above-described preferred embodiment. In the blower apparatus 1A according to the modification illustrated in FIG. 6, an air blowing portion 40A includes a plurality of flat plates 410A, similarly to the air blowing portion 40 according to the above-described preferred embodiment. The flat plates 410A include a top flat plate 411A, which is arranged at the highest position. In addition, an upper plate portion 23A of a housing 20A includes an air inlet 202A arranged to pass therethrough in the vertical direction.

In this blower apparatus 1A, the top flat plate 411A is arranged radially inward of an inner edge portion 231A of the upper plate portion 23A when viewed in the axial direction, the inner edge portion 231A defining the air inlet 202A. In addition, the top flat plate 411A and the upper plate portion 23A are arranged to radially overlap in part with each other. The blower apparatus 1A is able to achieve a further reduced thickness since the upper plate portion 23A and the top flat plate 411A are arranged to radially overlap with each other as described above.

FIG. 7 is a partial sectional view of a blower apparatus 1B according to another modification of the above-described preferred embodiment. In the blower apparatus 1B according to the modification illustrated in FIG. 7, an air blowing portion 40B includes a plurality of flat plates 410B. The flat plates 410B are arranged in the axial direction with an axial gap 400B defined between adjacent ones of the flat plates 410B. The flat plates 410B include a top flat plate 411B, which is arranged at the highest position, and a bottom flat plate 412B, which is arranged at the lowest position. Four of the flat plates 410B are arranged between the top flat plate 411B and the bottom flat plate 412B, and the highest one of the four flat plates 410B is referred to as a first intermediate flat plate 414B, and the remaining three flat plates 410B are each referred to as a second intermediate flat plate 415B. In addition, an upper plate portion 23B of a housing 20B includes an air inlet 202B arranged to pass therethrough in the vertical direction.

In this blower apparatus 1B, an outer edge of the top flat plate 411B is arranged radially inward of an inner edge portion 231B of the upper plate portion 23B when viewed in the axial direction, the inner edge portion 231B defining the air inlet 202B. In addition, the top flat plate 411B and the upper plate portion 23B are arranged to radially overlap at least in part with each other. Further, an outer edge of each of the bottom flat plate 412B, the first intermediate flat plate 414B, and the three second intermediate flat plates 415B is arranged below the upper plate portion 23B and radially outward of the air inlet 202B. That is, at least one of the flat plates 410B includes an outer edge arranged below the upper plate portion 23B and radially outward of the air inlet 202B. Here, an axial distance D3 between the upper plate portion 23B and the first intermediate flat plate 414B, which is the highest one of the bottom flat plate 412B, the first intermediate flat plate 414B, and the three second intermediate flat plates 415B, is arranged to be smaller than an axial dimension D4 of the axial gap 400B.

A pressure generated by rotation of the air blowing portion 40B spreads only a certain distance from a surface of each flat plate 410B. Therefore, a large distance between the upper plate portion 23B and the first intermediate flat plate 414B, which is the closest to the upper plate portion 23B of all the flat plates 410B that are arranged to axially overlap with the upper plate portion 23B, might produce a region in which the pressure generated by the rotation of the air blowing portion 40B does not act between the first intermediate flat plate 414B and the upper plate portion 23B. In the modification illustrated in FIG. 7, the distance D3 between the upper plate portion 23B and the first intermediate flat plate 414B, which is the closest to the upper plate portion 23B, is arranged to be small enough to achieve an improvement in static pressure between the first intermediate flat plate 414B and the upper plate portion 23B. This in turn leads to an increase in the volume of air to be discharged from the blower apparatus 1B.

FIG. 8 is a partial sectional view of a blower apparatus 1C according to yet another modification of the above-described preferred embodiment. In the blower apparatus 1C according to the modification illustrated in FIG. 8, an air blowing portion 40C includes a plurality of flat plates 410C. The flat plates 410C include a top flat plate 411C, which is arranged at the highest position, a bottom flat plate 412C, which is arranged at the lowest position, and four flat plates 410C arranged between the top flat plate 411C and the bottom flat plate 412C. The four flat plates 410C arranged between the top flat plate 411C and the bottom flat plate 412C will be hereinafter referred to as, from highest to lowest, a first intermediate flat plate 414C, a second intermediate flat plate 415C, a third intermediate flat plate 416C, and a fourth intermediate flat plate 417C. In addition, an upper plate portion 23C of a housing 20C includes an air inlet 202C arranged to pass therethrough in the vertical direction.

In this blower apparatus 1C, an outer edge of each of the top flat plate 411C and the first intermediate flat plate 414C is arranged radially inward of an inner edge portion 231C of the upper plate portion 23C when viewed in the axial direction, the inner edge portion 231C defining the air inlet 202C. Therefore, a large radial distance D5 between the outer edge of the top flat plate 411C and the inner edge portion 231C might permit a backflow phenomenon to occur in a gap between the outer edge of the top flat plate 411C and the inner edge portion 231C.

An outer edge of each of the second intermediate flat plate 415C, the third intermediate flat plate 416C, the fourth intermediate flat plate 417C, and the bottom flat plate 412C is arranged below the upper plate portion 23C and radially outward of the air inlet 202C. That is, at least, one of the flat, plates 410C includes an outer edge arranged below the upper plate portion 23C and radially outward of the air inlet 202C. Here, the axial distance between the upper plate portion 23C and the second intermediate flat plate 415C, which is arranged at the highest position of these four flat plates 410C, will be referred to as an axial distance D6.

In the modification illustrated in FIG. 8, the radial distance D5 between the outer edge of the top flat plate 411C and the inner edge portion 231C is arranged to be smaller than the axial distance D6 between the second intermediate flat plate 415C and the upper plate portion 23C. This contributes to preventing a backflow phenomenon from occurring in the gap between the outer edge of the top flat plate 411C and the inner edge portion 231C. This in turn leads to improved air blowing efficiency.

FIG. 9 is a partial sectional view of a blower apparatus 1D according to yet another modification of the above-described preferred embodiment. In the blower apparatus 1D according to the modification illustrated in FIG. 9, an air blowing portion 40D includes a plurality of flat plates 410D. The flat plates 410D include a top flat plate 411D, which is arranged at the highest position, a bottom flat plate 412D, which is arranged at the lowest position, and four intermediate flat plates 413D, which are arranged between the top flat plate 411D and the bottom flat plate 412D.

In this blower apparatus 1D, all of the flat plates 410D, including the bottom flat plate 412D, include air holes 60D arranged to pass therethrough in the axial direction. The air holes 60D defined in the bottom flat plate 4120 allow gas supplied into a housing 20D through an air inlet 202D to be supplied to a space on the lower side of the bottom flat plate 412D. This leads to an increase in the volume of air to be discharged from the blower apparatus 1D,

FIG. 10 is a partial sectional view of a blower apparatus 1E according to yet another modification of the above-described preferred embodiment. In the blower apparatus 1E according to the modification illustrated in FIG. 10, an air blowing portion 40E includes a plurality of flat plates 410E. The flat plates 410E include a top flat plate 411E, which is arranged at the highest position, a bottom flat plate 412E, which is arranged at the lowest position, and four flat plates 410E arranged between the top flat plate 411E and the bottom flat plate 412E. The four flat plates 410E arranged between the top flat plate 411E and the bottom flat plate 412E will be hereinafter referred to as, from highest to lowest, a first intermediate flat plate 414E, a second intermediate flat plate 415E, a third intermediate flat plate 416E, and a fourth intermediate flat plate 417E.

In this blower apparatus 1E, an upper plate portion 23E of a housing 20E includes a first air inlet 202E arranged to pass therethrough in the vertical direction. A lower plate portion 21E of the housing 20E includes a second air inlet 203E arranged to pass therethrough in the vertical direction. In addition, each of the top flat plate 411E, the first intermediate flat plate 414E, the second intermediate flat plate 415E, the fourth intermediate flat plate 417E, and the bottom flat plate 412E includes air holes 60E. Meanwhile, the third intermediate flat plate 416E includes no air hole 60E.

Thus, gas supplied into the housing 20E through the first air inlet 202E travels downward through the air holes 60E of the top flat plate 411E, the first intermediate flat plate 414E, and the second intermediate flat plate 415E toward an upper surface of the third intermediate flat plate 416E. Gas is thus supplied to three axial gaps 400E arranged above the third intermediate flat plate 416E. Meanwhile, gas supplied into the housing 20E through the second air inlet 203E travels upward through the air holes 60E of the bottom flat plate 412E and the fourth intermediate flat plate 417E toward a lower surface of the third intermediate flat plate 416E. Gas is thus supplied to two axial gaps 400E arranged below the third intermediate flat plate 416E.

As described above, in this blower apparatus 1E, gas is supplied from both the upper and lower sides of the air blowing portion 40E. Therefore, even if the number of flat plates 410E is increased, a sufficient volume of gas can be supplied to each axial gap 400E. Accordingly, the blower apparatus 1E is able to achieve improved air blowing efficiency.

In addition, in this blower apparatus 1E, the third intermediate flat plate 416E, which is arranged near the middle of the plurality of flat plates 410E, includes no air hole 60E. This prevents the gas supplied from the upper side and the gas supplied from the lower side from colliding against each other to cause a turbulent flow. This contributes to preventing an increase in noise.

FIG. 11 is a partial sectional view of a blower apparatus 1F according to yet another modification of the above-described preferred embodiment. In the blower apparatus 1F according to the modification illustrated in FIG. 11, an air blowing portion 40F includes a plurality of flat plates 410F. The flat plates 410F include a top flat plate 411F, which is arranged at the highest position, a bottom flat plate 412F, which is arranged at the lowest position, and four intermediate flat plates 413F, which are arranged between the top flat plate 411F and the bottom flat plate 412F.

In this blower apparatus 1F, each of the top flat plate 411F and the bottom flat plate 412F is arranged to have an axial thickness greater than an axial thickness of each of the intermediate flat plates 413F. Thus, the top flat plate 411F and the bottom flat plate 412F are less easily deformed than the other flat plates 410F.

On both the upper and lower sides of each intermediate flat plate 413F, other ones of the flat plates 410F are arranged. Therefore, an upper surface of each intermediate flat plate 413F receives a pressure of an air flow generated by a lower surface of the flat plate 410F arranged on the upper side. Meanwhile, a lower surface of each intermediate flat plate 413F receives a pressure of an air flow generated by an upper surface of the flat plate 410F arranged on the lower side. Thus, both the upper and lower surfaces of each intermediate flat plate 413F receive the pressures from adjacent ones of the flat plates 410F. This allows each intermediate flat plate 413F to stably rotate.

Meanwhile, a lower surface of the top flat plate 411F receives a pressure from an adjacent one of the flat plates 410F, while an upper surface of the top flat plate 411F receives little pressure. In addition, an upper surface of the bottom flat plate 412F receives a pressure from an adjacent one of the flat plates 410F, while a lower surface of the bottom flat plate 412F receives little pressure. Therefore, both the top flat plate 411F and the bottom flat plate 412F tend to more easily wobble up and down than the intermediate flat plates 413F.

In this blower apparatus 1F, the axial thickness of each of the top flat plate 411F and the bottom flat plate 412F is made greater than the axial thickness of any other flat plate 410F to reduce the likelihood of a deformation of each of the top flat plate 411F and the bottom flat plate 412F. This reduces the likelihood that each of the top flat plate 411F and the bottom flat plate 412F will be brought into contact with another member, such as, for example, an adjacent one of the flat plates 410F or a housing 20F.

FIG. 12 is a partial sectional view of a blower apparatus 1G according to yet another modification of the above-described preferred embodiment. In the blower apparatus 1G according to the modification illustrated in FIG. 12, an air blowing portion 40G includes a plurality of flat plates 410G. Each of the flat plates 410G includes an outer end portion having a thickness gradually decreasing in a radially outward direction.

If each flat plate 410G had a uniform axial thickness even at the outer end portion thereof, the outer end portion of the flat plate 410G would have a cylindrical outer end surface. In this case, a junction of the outer end surface with an upper surface of the flat plate 410G, and a junction of the outer end surface with a lower surface of the flat plate 410G, would both be angular. Accordingly, an eddy might occur in an air flow around each junction. Such an eddy in the air flow might result in reduced air blowing efficiency and in noise.

In this blower apparatus 1G, the outer end portion of each flat plate 410G is arranged to have a thickness gradually decreasing in the radially outward direction to reduce the likelihood of an occurrence of an eddy in an air flow. This leads to improved air blowing efficiency and reduced noise.

FIG. 13 is a partial sectional view of a blower apparatus 1H according to yet another modification of the above-described preferred embodiment. In the blower apparatus 1H according to the modification illustrated in FIG. 13, an air blowing portion 40H includes a plurality of flat plates 410H. In addition, an upper plate portion 23H of a housing 20H includes an air inlet 202H arranged to pass therethrough in the vertical direction. In other words, the upper plate portion 23H includes an inner edge portion 231H arranged to define the air inlet 202H.

In this blower apparatus 1H, an elastic member 24H is arranged on a lower surface of the upper plate portion 23H. The elastic member 24H is arranged along the inner edge portion 231H to surround the inner edge portion 231H. In addition, an outer edge of each flat plate 410H is arranged radially outward of the air inlet 202H. Thus, the outer edge of each flat plate 410H is arranged at a position axially overlapping with the upper plate portion 23H. Since the elastic member 24H is arranged around the inner edge portion 231H, even if any flat plate 410H bends significantly, the flat plate 410H will not make direct contact with the upper plate portion 23H, making contact with the elastic member 24H instead. This contributes to preventing each of the flat plates 410H and the upper plate portion 23H from being damaged.

FIG. 14 is a partial sectional view of a blower apparatus 1J according to yet another modification of the above-described preferred embodiment. In the blower apparatus 1J according to the modification illustrated in FIG. 14, a motor portion 30J includes a stationary portion 31J, a rotating portion 32J, and two ball bearings 33J.

The stationary portion 31J includes a stator fixing portion 311J and a stator 312J. The stator fixing portion 311J is a member being cylindrical and having a closed bottom and fixed to a housing 20J. The stator 312J is an armature fixed to an outer circumferential surface of the stator fixing portion 311J.

The rotating portion 32J includes a shaft 321J, a hub 322J, and a magnet 324J. At least a lower end portion of the shaft 321J is arranged inside of the stator fixing portion 311J. In addition, an upper end portion of the shaft 321J is fixed to the hub 322J. The magnet 324J is fixed to the hub 322J. The magnet 324J is arranged radially opposite to the stator 312J.

Each ball bearing 33J is arranged to connect the rotating portion 32J to the stationary portion 31J such that the rotating portion 32J is rotatable with respect to the stationary portion 31J. Specifically, an outer race of each ball bearing 33J is fixed to an inner circumferential surface of the stator fixing portion 311J of the stationary portion 31J. In addition, an inner race of each ball bearing 33J is fixed to an outer circumferential surface of the shaft 321J of the rotating portion 32J. Further, a plurality of balls, each of which is a spherical rolling element, are arranged between the outer race and the inner race. As described above, instead of a fluid dynamic bearing, rolling-element bearings, such as, for example, ball bearings, may be used as a bearing structure of the motor portion 30J.

In the modification illustrated in FIG. 14, the motor portion 30J includes the two ball bearings 33J. The ball bearings 33J are arranged near an upper end and a lower end of an axial range over which the inner circumferential surface of the stator fixing portion 311J and the shaft 321J are opposed to each other. This contributes to preventing the shaft 321J from being inclined with respect to a central axis 9J.

FIG. 15 is a top view of a blower apparatus 1K according to yet another modification of the above-described preferred embodiment. In the blower apparatus 1K according to the modification illustrated in FIG. 15, a housing 20K includes a plurality of air outlets 201K. Specifically, a side wall portion 22K includes the air outlets 201K, each of which is arranged to face in a radial direction, at a plurality of circumferential positions. The housing 20K includes tongue portions 203K, each of which is arranged near a separate one of the air outlets 201K. In addition, an air blowing portion 40K includes a plurality of flat plates 410K arranged in the axial direction with an axial gap defined between adjacent ones of the flat plates 410K.

In a centrifugal fan including an impeller, periodic noise occurs owing to the shape, number, arrangement, and so on of blades. In addition, such noise tends to easily occur around a tongue portion. Accordingly, when air is to be discharged in a plurality of directions, a deterioration in noise characteristics occurs because of an increased number of tongue portions. However, in this blower apparatus 1K, air flows traveling radially outward are generated by rotation of the flat plates 410K, and therefore, the blower apparatus 1K is able to achieve reduced periodic noise when compared to the centrifugal fan including the impeller. Therefore, the blower apparatus 1K, which is designed to discharge air in a plurality of directions, does not significantly deteriorate in noise characteristics doe to the tongue portions 203K.

Note that, although the number of flat plates included in the air blowing portion is six in each of the above-described preferred embodiment and the modifications thereof, this is not essential to the present invention. The number of flat plates may alternatively be two, three, four, five, or more than six.

Also note that, although the hub is defined by two members, i.e., the hub body member and the flange member, in each of the above-described preferred embodiment and the modifications thereof, this is not essential to the present invention. The hub may alternatively be defined by a single member, or three or more members.

Also note that the detailed shape of any member may be different from the shape thereof as illustrated in the accompanying drawings of the present application. For example, the shape of any of the housing, the air blowing portion, and the motor portion may be different from that according to each of the above-described preferred embodiment and the modifications thereof. Also note that features of the above-described preferred embodiment and the modifications thereof may be combined appropriately as long as no conflict arises.

Preferred embodiments of the present invention are applicable to blower apparatuses.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims. 

What is claimed is:
 1. A blower apparatus comprising: an air blowing portion arranged to rotate about a central axis extending in a vertical direction; a motor portion arranged to rotate the air blowing portion; and a housing arranged to house the air blowing portion and the motor portion; wherein the housing includes: a lower plate portion arranged to cover at least a portion of a lower side of the air blowing portion, and support, the motor portion; an upper plate portion arranged above the lower plate portion, and including an air inlet arranged to pass therethrough in an axial direction; and a side wall portion arranged to cover a lateral side of the air blowing portion between the upper plate portion and the lower plate portion, and including an air outlet arranged to face in a radial direction at at least one circumferential position; the air blowing portion includes a plurality of flat plates arranged in the axial direction with an axial gap defined between adjacent ones of the flat plates; at least one of the flat plates includes an air hole arranged to pass therethrough in the axial direction; and each air hole is arranged to be in communication with a space radially outside of the air blowing portion through the axial gap.
 2. The blower apparatus according to claim 1, wherein the flat plates include a top flat plate arranged at a highest position of all the flat plates, the top flat plate being arranged axially below and radially inward of an inner edge portion of the upper plate portion when viewed in the axial direction, the inner edge portion defining the air inlet; and an axial distance between an outer edge of the top flat plate and the inner edge portion is arranged to be smaller than a radial distance between the outer edge of the top flat plate and the inner edge portion,
 3. The blower apparatus according to claim 1, wherein the flat plates include a top flat plate arranged at a highest position of all the flat plates, the top flat plate being arranged radially inward of an inner edge portion of the upper plate portion when viewed in the axial direction, the inner edge portion defining the air inlet; and the top flat plate and the upper plate portion are arranged to radially overlap at least in part with each other.
 4. The blower apparatus according to claim 1, wherein at least one of the flat plates includes an outer edge arranged below the upper plate portion and radially outward of the air inlet; and an axial distance between the upper plate portion and a highest one of the at least one of the flat plates is arranged to be smaller than an axial dimension of the axial gap.
 5. The blower apparatus according to claim 1, wherein the flat plates include a top flat plate arranged at a highest position of all the flat plates, the top flat plate being arranged radially inward of an inner edge portion of the upper plate portion when viewed in the axial direction, the inner edge portion defining the air inlet; at least one of the flat plates includes an outer edge arranged below the upper plate portion and radially outward of the inner edge portion; and a radial distance between an outer edge of the top flat plate and the inner edge portion is arranged to be smaller than an axial distance between the upper plate portion and a highest one of the at least one of the flat plates.
 6. The blower apparatus according to claim 1, wherein the flat plates include a bottom flat plate arranged at a lowest position of all the flat plates, the bottom flat plate including the air hole arranged to pass therethrough in the axial direction.
 7. The blower apparatus according to claim 1, wherein the flat plates include a bottom flat plate arranged at a lowest position of all the flat plates, the bottom flat plate including no air hole arranged to pass therethrough in the axial direction.
 8. The blower apparatus according to claim 1, wherein the flat plates include a top flat plate arranged at a highest position of all the flat plates, and a bottom flat plate arranged at a lowest position of all the flat plates; and each of the top flat plate and the bottom flat plate is arranged to have a thickness greater than a thickness of each remaining flat plate.
 9. The blower apparatus according to claim 1, wherein at least one of the flat plates includes an outer end portion having a thickness gradually decreasing in a radially outward direction.
 10. The blower apparatus according to claim 1, further comprising an elastic member arranged on a lower surface of the upper plate portion, wherein the elastic member is arranged along an inner edge portion of the upper plate portion, the inner edge portion defining the air inlet.
 11. The blower apparatus according to claim 1, wherein a center of the air inlet is arranged to coincide with the central axis.
 12. The blower apparatus according to claim 1, wherein the motor portion includes: a stationary portion including an armature and a bearing housing; and a rotating portion including a shaft, a bearing member, and a magnet arranged radially opposite to the armature; the bearing housing and a combination of the shaft and the bearing member are arranged to have a lubricating fluid therebetween; the bearing housing and the rotating portion are arranged to together define a gap defining a seal portion therebetween, the seal portion having a surface of the lubricating fluid defined therein; and in the seal portion, a distance between the bearing housing and the rotating portion is arranged to increase with increasing distance from the surface of the lubricating fluid.
 13. The blower apparatus according to claim 1, wherein the motor portion includes: a stationary portion including an armature; a rotating portion including a magnet arranged radially opposite to the armature; and a ball bearing arranged to connect the rotating portion to the stationary portion such that the rotating portion is rotatable with respect to the stationary portion.
 14. The blower apparatus according to claim 1, wherein the side wall portion includes a plurality of the air outlets at a plurality of circumferential positions. 